In Patent Literature 1, there is proposed a technology in which, from a photographed image, a physical quantity of an object is estimated by a particle filter method, or a position of an object is estimated by a condensation method while using a quantity related to a feature quantity of the object being used as a weight.
In Patent Literature 2, there is proposed a technology in which a three-dimensional model is projected to a two-dimensional observation space, the three-dimensional model being configured with a plurality of feature points and partial image information, the feature points having three-dimensional coordinate values, the partial image information expressing a partial image associated with each feature point, a state quantity of the three-dimensional model is estimated using a feature point set selected in the two-dimensional observation space, the estimated three-dimensional model state is projected to an observation space, the adaptability is calculated repeatedly, and the state quantity of the three-dimensional model is estimated.
In Patent Literature 3, there is proposed a technology in which watching regions for determining presence/absence of a target are set one by one at a plurality of positions in an image, a reference position of parts of a case where the target is assumed to exist at the watching region is set based on a deformable part model, a deformation cost is calculated for each of the parts detected, the deformation cost being a value that expresses the degree of the deviation from the reference position, and the watching region is determined to be a target region where the target configuring a group exists with a condition that the parts of a same kind whose deformation cost calculated is within a predetermined range exist by a plurality.